Charge-per-click web advertising is a form of advertising on the Internet whereby an advertisement with an associated link is displayed on a website, and a fee is charged to the advertiser by the entity hosting the website in the event that a visitor of the website actually clicks or otherwise selects the advertising link to open that link in the web browser. The fee charge is transparent to the visitor, but a record of the click is recorded so that payment can be effected from the advertiser to the host.
Click fraud (also known as click spam) occur when an adverting link on a web-page is selected, either automatically (e.g. by a script or computer program), or manually (e.g. by a user) in order to generate a charge-per-click, yet where there is in fact no interest in contents of the advertisement. More generally, click fraud also occurs in any situation where an artificial attempt is made to inflate web traffic to a particular website. Click fraud is the subject of some controversy and increasing litigation due to the advertising networks being a key beneficiary of the fraud.
In summary, click fraud creates fake requests to a web link to inflate traffic statistics or trigger revenue recognition. The usual method of detection is to record the Internet Protocol (“IP”) address of the client. Repeated requests in a short time by the same client can be identified as spam. One problem is that this collection of IP addresses also allows profiling the activities of legitimate users. This profiling reduces the privacy of the legitimate user.